While there are still many questions about just how much Snowden himself leaked to the press, how much access he really had to the classified program, and how he took it, the case opens a new chapter on insider threat risks. Snowden is not the first insider to drop sensitive information externally, and his leak has some parallels to that of Bradley Manning's case. But the massive disclosure of classified and top secret NSA information represents a whole new scale of information leakage that security experts say could be the point of no return for keeping data secret in this new age of disclosure that in large part is driven by online access and abundant opportunity for dissemination.

"I think this is another milestone, and it's going to become much more prevalent over the next 10 years -- the dissemination of sensitive information," says James C. Foster, founder and CEO of Riskive, and who also once worked for Booz Allen. "It's going to be a significant challenge in keeping sensitive information in the right hands. As we've seen with WikiLeaks and Snowden, if one person sets their mind to it, they will grab information and find a way to disseminate it."

Most enterprises don't have the same level of sensitive and classified information to protect that the NSA does, but the core challenges of stopping a determined insider from leaking what he or she knows or has access to are the same: There's no guaranteed way to stop it.

"You would hope that the National Security Agency would be really good at keeping secrets ... but it seems someone let the cat out of the bag on this occasion with awkward results," says Graham Cluley, senior technology consultant at Sophos. "The truth is that organizations big and small can still make mistakes or trust someone they shouldn't have to keep their sensitive data private."

Foster says it's an eerily similar conundrum to preventing an individual terrorist willing to sacrifice himself for a cause. "Unfortunately, the reality is similar to the difficulty in stopping individual motivated terrorists. It's hard to identify an individual and prevent" them from carrying out a leak if they are willing to face the consequences, he says.

According to The Guardian, which first broke the story after receiving information from Snowden, the whistleblower wrote this in a note with the NSA documents he handed to the publication: "I understand that I will be made to suffer for my actions ... [but] I will be satisfied if the federation of secret law, unequal pardon and irresistible executive powers that rule the world that I love are revealed even for an instant."

[Massive information-sharing program involves Google, Facebook, and other technology heavyweights, top secret document details. But NSA looks to have acted inside the law. See NSA PRISM Creates Stir, But Appears Legal.]

Bruce Schneier, renowned security expert and CTO of BT Counterpane, says if your organization isn't doing anything illegal, it has nothing to fear from whistleblowers such as Snowden. But you can't stop a determined insider from leaking information. "In general, you have to trust people inside your system," he said in an email exchange. "They can betray that trust. You can mitigate that risk by trusting them less, but that's about it."

NSA's leak raises more questions about who has access to what and why, and how a top secret program could be leaked by a 29-year-old at a relatively low-level position who had worked with NSA as a contractor over the past four years, with Booz Allen, Dell, and other contractors. And just how the most secretive agency in the government could allow such a leak to occur has baffled most security experts: "I'm just in shock that [Snowden] was able to [do this]," says Jared Thorkelson, principal with DLP Experts, an expert on insider threat issues.

The NSA leak also provides some lessons for businesses. "These are all the same concerns for commercial enterprises; It's not that different. The NSA has a different set of secrets, but [organizations] all have the same types of scenarios you need to prevent this type of information leaking outside or falling into the wrong hands. Those technologies are used in both the public and private sectors," Thorkelson says.

So it's time to revisit some controls around sensitive data and employees and contractors, security experts say. Here are some key questions to consider:

What Access Do Your Own Users Have?
If Snowden indeed had authorized access to the NSA classified information he leaked, then catching him the act of attempting to or somehow accessing it would be difficult. "Authorized users are authorized users," says Andy Hubbard, senior security consultant at Neohapsis. The data he grabbed may have come from an external source, such as a reporting server or logging system, he says -- systems that wouldn't have as many data-extraction controls, he says.

Ideally, organizations need to establish access controls for their sensitive data. But that initially involves identifying the sensitive data, he says.

They also should adopt least privilege access policies where users and contractors are only allowed to see and access data they need for their jobs. "You need to set aside a little time to see who has access to what and actually identify specific access controls," he says. A user audit is a handy tool for this, according to Hubbard.

The bottom line is that in many cases, users have way too much access to data. "Systems administrators, in particular, although low level, typically have the highest access to systems and data, given they manage those systems. Without implementing adequate role-based access controls based on least-privileged access, companies and organizations are granting god-like access to their systems administrators," says Eric Chiu, president & founder of HyTrust.

Next Page: Limiting contractor access/

What Access Do Your Contractors Have?
Plenty of technologies are available for limiting contractor access to data, DLP Experts' Thorkelson says. "Identity access management and those kinds of technologies ... why not use these technologies that keep data from being shared with other people?" he says.

More thorough vetting of contractors and employees is another best practice organizations should adopt during the hiring process, Neohapsis' Hubbard says. "A lot of organizations feel there's a one-size-fits-all in the background check process," he says. But that's not the case, so organizations should stay on top of what background checks providers use to investigate employees and contractors who will be handling sensitive data, he says.

According to Carnegie Mellon University’s CERT Insider Threat Center, prevention of an insider attack or leak is key. "At the least, you need to organize a well-thought-out insider threat program that can help protect you and deter other incidents like workplace violence," says Mike Theis, chief counterintelligence expert at Carnegie Mellon University’s CERT Insider Threat Center, in a recent interview with Dark Reading. Theis declined to be interviewed for this article, citing the ongoing investigation of the NSA and Snowden leak case.

For mitigating insider threats, CERT publishes the Common Sense Guide To Insider Threat, which provides best practices, such as documenting and consistently enforcing policies and controls, adopting least privilege and enforcing separation of duties, and incorporating insider threat awareness into security training programs.

"If someone might be turning bad, there still is an opportunity to stop" and prevent them from acting, Theis says.

Remotely located users or contractors are not always well-monitored. Snowden, for example, worked for Booz Allen on the NSA contract as part of a small unit in Hawaii. "Management has the responsibility for oversight of its workforce members, but, unfortunately, they don't [often] take an active role," Hubbard says.

In the case of contractors working for the intelligence community, it's difficult to spot a leak, however. "They're going to have access," Riskive's Foster says. "There are a lot of processes in place on the government side and on the contractor side to safely handle that data," but if they have legitimate access, it's difficult to determine foul play.

How Are You Monitoring User Activity?
Reassessing user behavior and movement of data is another key best practice to helping minimize the risk of a big, sensitive insider leak.

Identity access management and data loss prevention (DLP) can help here. DLP products can be configured to prevent physical printing of certain documents, for instance, and USB ports can be disabled to prevent siphoning onto removable drives.

"Remote access systems don't have excellent reporting, so you'll typically have to dump logging and auditing off into a security event monitoring system and do some trending over time," Neohapsis' Hubbard says. "If you have some sort of centralized auditing tool, that's something very easy to start identifying thresholds for worker activity," he says.

But most of these controls are looking for outliers, not authorized users performing authorized actions, he says. Critical or classified files can be more closely monitored, too.

The trade-off, of course, is productivity. "The more you lock down environments, the more you damage workflow," Hubbard says.

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Kelly Jackson Higgins is Executive Editor at DarkReading.com. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio